tests.rs

		assert_eq!(Balances::total_balance(&10), 1);
		// check the balance of a validator's stash accounts.
		assert_eq!(Balances::total_balance(&11), stash_initial_balance);
		// and the nominator (to-be)
		let _ = Balances::make_free_balance_be(&2, 500);

		// add a dummy nominator.
		<Stakers<Test>>::insert(&11, Exposure {
			own: 500, // equal division indicates that the reward will be equally divided among validator and nominator.
			total: 1000,
			others: vec![IndividualExposure {who: 2, value: 500 }]
		});
		<Payee<Test>>::insert(&2, RewardDestination::Stash);
		<Validators<Test>>::insert(&11, ValidatorPrefs {
			commission: Perbill::from_percent(50),
		});

		// Compute total payout now for whole duration as other parameter won't change
		let total_payout_0 = current_total_payout_for_duration(3000);
		assert!(total_payout_0 > 100); // Test is meaningfull if reward something
		<Module<Test>>::reward_by_ids(vec![(11, 1)]);

		start_era(1);

		// whats left to be shared is the sum of 3 rounds minus the validator's cut.
		let shared_cut = total_payout_0 / 2;
		// Validator's payee is Staked account, 11, reward will be paid here.
		assert_eq!(Balances::total_balance(&11), stash_initial_balance + shared_cut / 2 + shared_cut);
		// Controller account will not get any reward.
		assert_eq!(Balances::total_balance(&10), 1);
		// Rest of the reward will be shared and paid to the nominator in stake.
		assert_eq!(Balances::total_balance(&2), 500 + shared_cut / 2);

		check_exposure_all();
		check_nominator_all();
	});

}

#[test]
fn bond_extra_works() {
	// Tests that extra `free_balance` in the stash can be added to stake
	// NOTE: this tests only verifies `StakingLedger` for correct updates
	// See `bond_extra_and_withdraw_unbonded_works` for more details and updates on `Exposure`.
	ExtBuilder::default().build().execute_with(|| {
		// Check that account 10 is a validator
		assert!(<Validators<Test>>::exists(11));
		// Check that account 10 is bonded to account 11
		assert_eq!(Staking::bonded(&11), Some(10));
		// Check how much is at stake
		assert_eq!(Staking::ledger(&10), Some(StakingLedger {
			stash: 11,
			total: 1000,
			active: 1000,
			unlocking: vec![],
		}));

		// Give account 11 some large free balance greater than total
		let _ = Balances::make_free_balance_be(&11, 1000000);

		// Call the bond_extra function from controller, add only 100
		assert_ok!(Staking::bond_extra(Origin::signed(11), 100));
		// There should be 100 more `total` and `active` in the ledger
		assert_eq!(Staking::ledger(&10), Some(StakingLedger {
			stash: 11,
			total: 1000 + 100,
			active: 1000 + 100,
			unlocking: vec![],
		}));

		// Call the bond_extra function with a large number, should handle it
		assert_ok!(Staking::bond_extra(Origin::signed(11), u64::max_value()));
		// The full amount of the funds should now be in the total and active
		assert_eq!(Staking::ledger(&10), Some(StakingLedger {
			stash: 11,
			total: 1000000,
			active: 1000000,
			unlocking: vec![],
		}));
	});
}

#[test]
fn bond_extra_and_withdraw_unbonded_works() {
	// * Should test
	// * Given an account being bonded [and chosen as a validator](not mandatory)
	// * It can add extra funds to the bonded account.
	// * it can unbond a portion of its funds from the stash account.
	// * Once the unbonding period is done, it can actually take the funds out of the stash.
	ExtBuilder::default().nominate(false).build().execute_with(|| {
		// Set payee to controller. avoids confusion
		assert_ok!(Staking::set_payee(Origin::signed(10), RewardDestination::Controller));

		// Give account 11 some large free balance greater than total
		let _ = Balances::make_free_balance_be(&11, 1000000);

		// Initial config should be correct
		assert_eq!(Staking::current_era(), 0);
		assert_eq!(Session::current_index(), 0);

		// check the balance of a validator accounts.
		assert_eq!(Balances::total_balance(&10), 1);

		// confirm that 10 is a normal validator and gets paid at the end of the era.
		start_era(1);

		// Initial state of 10
		assert_eq!(Staking::ledger(&10), Some(StakingLedger {
			stash: 11,
			total: 1000,
			active: 1000,
			unlocking: vec![],
		}));
		assert_eq!(Staking::stakers(&11), Exposure { total: 1000, own: 1000, others: vec![] });

		// deposit the extra 100 units
		Staking::bond_extra(Origin::signed(11), 100).unwrap();

		assert_eq!(Staking::ledger(&10), Some(StakingLedger {
			stash: 11,
			total: 1000 + 100,
			active: 1000 + 100,
			unlocking: vec![],
		}));
		// Exposure is a snapshot! only updated after the next era update.
		assert_ne!(Staking::stakers(&11), Exposure { total: 1000 + 100, own: 1000 + 100, others: vec![] });

		// trigger next era.
		Timestamp::set_timestamp(10);
		start_era(2);
		assert_eq!(Staking::current_era(), 2);

		// ledger should be the same.
		assert_eq!(Staking::ledger(&10), Some(StakingLedger {
			stash: 11,
			total: 1000 + 100,
			active: 1000 + 100,
			unlocking: vec![],
		}));
		// Exposure is now updated.
		assert_eq!(Staking::stakers(&11), Exposure { total: 1000 + 100, own: 1000 + 100, others: vec![] });

		// Unbond almost all of the funds in stash.
		Staking::unbond(Origin::signed(10), 1000).unwrap();
		assert_eq!(Staking::ledger(&10), Some(StakingLedger {
			stash: 11, total: 1000 + 100, active: 100, unlocking: vec![UnlockChunk{ value: 1000, era: 2 + 3}] })
		);

		// Attempting to free the balances now will fail. 2 eras need to pass.
		Staking::withdraw_unbonded(Origin::signed(10)).unwrap();
		assert_eq!(Staking::ledger(&10), Some(StakingLedger {
			stash: 11, total: 1000 + 100, active: 100, unlocking: vec![UnlockChunk{ value: 1000, era: 2 + 3}] }));

		// trigger next era.
		start_era(3);

		// nothing yet
		Staking::withdraw_unbonded(Origin::signed(10)).unwrap();
		assert_eq!(Staking::ledger(&10), Some(StakingLedger {
			stash: 11, total: 1000 + 100, active: 100, unlocking: vec![UnlockChunk{ value: 1000, era: 2 + 3}] }));

		// trigger next era.
		start_era(5);

		Staking::withdraw_unbonded(Origin::signed(10)).unwrap();
		// Now the value is free and the staking ledger is updated.
		assert_eq!(Staking::ledger(&10), Some(StakingLedger {
			stash: 11, total: 100, active: 100, unlocking: vec![] }));
	})
}

#[test]
fn too_many_unbond_calls_should_not_work() {
	ExtBuilder::default().build().execute_with(|| {
		// locked at era 0 until 3
		for _ in 0..MAX_UNLOCKING_CHUNKS-1 {
			assert_ok!(Staking::unbond(Origin::signed(10), 1));
		}

		start_era(1);

		// locked at era 1 until 4
		assert_ok!(Staking::unbond(Origin::signed(10), 1));
		// can't do more.
		assert_noop!(Staking::unbond(Origin::signed(10), 1), Error::<Test>::NoMoreChunks);

		start_era(3);

		assert_noop!(Staking::unbond(Origin::signed(10), 1), Error::<Test>::NoMoreChunks);
		// free up.
		assert_ok!(Staking::withdraw_unbonded(Origin::signed(10)));

		// Can add again.
		assert_ok!(Staking::unbond(Origin::signed(10), 1));
		assert_eq!(Staking::ledger(&10).unwrap().unlocking.len(), 2);
	})
}

#[test]
fn rebond_works() {
	// * Should test
	// * Given an account being bonded [and chosen as a validator](not mandatory)
	// * it can unbond a portion of its funds from the stash account.
	// * it can re-bond a portion of the funds scheduled to unlock.
	ExtBuilder::default()
		.nominate(false)
		.build()
		.execute_with(|| {
			// Set payee to controller. avoids confusion
			assert_ok!(Staking::set_payee(
				Origin::signed(10),
				RewardDestination::Controller
			));

			// Give account 11 some large free balance greater than total
			let _ = Balances::make_free_balance_be(&11, 1000000);

			// confirm that 10 is a normal validator and gets paid at the end of the era.
			start_era(1);

			// Initial state of 10
			assert_eq!(
				Staking::ledger(&10),
				Some(StakingLedger {
					stash: 11,
					total: 1000,
					active: 1000,
					unlocking: vec![],
				})
			);

			start_era(2);
			assert_eq!(Staking::current_era(), 2);

			// Try to rebond some funds. We get an error since no fund is unbonded.
			assert_noop!(
				Staking::rebond(Origin::signed(10), 500),
				Error::<Test>::NoUnlockChunk,
			);

			// Unbond almost all of the funds in stash.
			Staking::unbond(Origin::signed(10), 900).unwrap();
			assert_eq!(
				Staking::ledger(&10),
				Some(StakingLedger {
					stash: 11,
					total: 1000,
					active: 100,
					unlocking: vec![UnlockChunk {
						value: 900,
						era: 2 + 3
					},]
				})
			);

			// Re-bond all the funds unbonded.
			Staking::rebond(Origin::signed(10), 900).unwrap();
			assert_eq!(
				Staking::ledger(&10),
				Some(StakingLedger {
					stash: 11,
					total: 1000,
					active: 1000,
					unlocking: vec![],
				})
			);

			// Unbond almost all of the funds in stash.
			Staking::unbond(Origin::signed(10), 900).unwrap();
			assert_eq!(
				Staking::ledger(&10),
				Some(StakingLedger {
					stash: 11,
					total: 1000,
					active: 100,
					unlocking: vec![UnlockChunk { value: 900, era: 5 }],
				})
			);

			// Re-bond part of the funds unbonded.
			Staking::rebond(Origin::signed(10), 500).unwrap();
			assert_eq!(
				Staking::ledger(&10),
				Some(StakingLedger {
					stash: 11,
					total: 1000,
					active: 600,
					unlocking: vec![UnlockChunk { value: 400, era: 5 }],
				})
			);

			// Re-bond the remainder of the funds unbonded.
			Staking::rebond(Origin::signed(10), 500).unwrap();
			assert_eq!(
				Staking::ledger(&10),
				Some(StakingLedger {
					stash: 11,
					total: 1000,
					active: 1000,
					unlocking: vec![]
				})
			);

			// Unbond parts of the funds in stash.
			Staking::unbond(Origin::signed(10), 300).unwrap();
			Staking::unbond(Origin::signed(10), 300).unwrap();
			Staking::unbond(Origin::signed(10), 300).unwrap();
			assert_eq!(
				Staking::ledger(&10),
				Some(StakingLedger {
					stash: 11,
					total: 1000,
					active: 100,
					unlocking: vec![
						UnlockChunk { value: 300, era: 5 },
						UnlockChunk { value: 300, era: 5 },
						UnlockChunk { value: 300, era: 5 },
					]
				})
			);

			// Re-bond part of the funds unbonded.
			Staking::rebond(Origin::signed(10), 500).unwrap();
			assert_eq!(
				Staking::ledger(&10),
				Some(StakingLedger {
					stash: 11,
					total: 1000,
					active: 600,
					unlocking: vec![
						UnlockChunk { value: 300, era: 5 },
						UnlockChunk { value: 100, era: 5 },
					]
				})
			);
		})
}

#[test]
fn slot_stake_is_least_staked_validator_and_exposure_defines_maximum_punishment() {
	// Test that slot_stake is determined by the least staked validator
	// Test that slot_stake is the maximum punishment that can happen to a validator
	ExtBuilder::default().nominate(false).fair(false).build().execute_with(|| {
		// Confirm validator count is 2
		assert_eq!(Staking::validator_count(), 2);
		// Confirm account 10 and 20 are validators
		assert!(<Validators<Test>>::exists(&11) && <Validators<Test>>::exists(&21));

		assert_eq!(Staking::stakers(&11).total, 1000);
		assert_eq!(Staking::stakers(&21).total, 2000);

		// Give the man some money.
		let _ = Balances::make_free_balance_be(&10, 1000);
		let _ = Balances::make_free_balance_be(&20, 1000);

		// We confirm initialized slot_stake is this value
		assert_eq!(Staking::slot_stake(), Staking::stakers(&11).total);

		// Now lets lower account 20 stake
		<Stakers<Test>>::insert(&21, Exposure { total: 69, own: 69, others: vec![] });
		assert_eq!(Staking::stakers(&21).total, 69);
		<Ledger<Test>>::insert(&20, StakingLedger { stash: 22, total: 69, active: 69, unlocking: vec![] });

		// Compute total payout now for whole duration as other parameter won't change
		let total_payout_0 = current_total_payout_for_duration(3000);
		assert!(total_payout_0 > 100); // Test is meaningfull if reward something
		<Module<Test>>::reward_by_ids(vec![(11, 1)]);
		<Module<Test>>::reward_by_ids(vec![(21, 1)]);

		// New era --> rewards are paid --> stakes are changed
		start_era(1);

		// -- new balances + reward
		assert_eq!(Staking::stakers(&11).total, 1000 + total_payout_0 / 2);
		assert_eq!(Staking::stakers(&21).total, 69 + total_payout_0 / 2);

		let _11_balance = Balances::free_balance(&11);
		assert_eq!(_11_balance, 1000 + total_payout_0 / 2);

		// -- slot stake should also be updated.
		assert_eq!(Staking::slot_stake(), 69 + total_payout_0 / 2);

		check_exposure_all();
		check_nominator_all();
	});
}

#[test]
fn on_free_balance_zero_stash_removes_validator() {
	// Tests that validator storage items are cleaned up when stash is empty
	// Tests that storage items are untouched when controller is empty
	ExtBuilder::default().existential_deposit(10).build().execute_with(|| {
		// Check the balance of the validator account
		assert_eq!(Balances::free_balance(&10), 256);
		// Check the balance of the stash account
		assert_eq!(Balances::free_balance(&11), 256000);
		// Check these two accounts are bonded
		assert_eq!(Staking::bonded(&11), Some(10));

		// Set some storage items which we expect to be cleaned up
		// Set payee information
		assert_ok!(Staking::set_payee(Origin::signed(10), RewardDestination::Stash));

		// Check storage items that should be cleaned up
		assert!(<Ledger<Test>>::exists(&10));
		assert!(<Bonded<Test>>::exists(&11));
		assert!(<Validators<Test>>::exists(&11));
		assert!(<Payee<Test>>::exists(&11));

		// Reduce free_balance of controller to 0
		let _ = Balances::slash(&10, u64::max_value());

		// Check the balance of the stash account has not been touched
		assert_eq!(Balances::free_balance(&11), 256000);
		// Check these two accounts are still bonded
		assert_eq!(Staking::bonded(&11), Some(10));

		// Check storage items have not changed
		assert!(<Ledger<Test>>::exists(&10));
		assert!(<Bonded<Test>>::exists(&11));
		assert!(<Validators<Test>>::exists(&11));
		assert!(<Payee<Test>>::exists(&11));

		// Reduce free_balance of stash to 0
		let _ = Balances::slash(&11, u64::max_value());
		// Check total balance of stash
		assert_eq!(Balances::total_balance(&11), 0);

		// Check storage items do not exist
		assert!(!<Ledger<Test>>::exists(&10));
		assert!(!<Bonded<Test>>::exists(&11));
		assert!(!<Validators<Test>>::exists(&11));
		assert!(!<Nominators<Test>>::exists(&11));
		assert!(!<Payee<Test>>::exists(&11));
	});
}

#[test]
fn on_free_balance_zero_stash_removes_nominator() {
	// Tests that nominator storage items are cleaned up when stash is empty
	// Tests that storage items are untouched when controller is empty
	ExtBuilder::default().existential_deposit(10).build().execute_with(|| {
		// Make 10 a nominator
		assert_ok!(Staking::nominate(Origin::signed(10), vec![20]));
		// Check that account 10 is a nominator
		assert!(<Nominators<Test>>::exists(11));
		// Check the balance of the nominator account
		assert_eq!(Balances::free_balance(&10), 256);
		// Check the balance of the stash account
		assert_eq!(Balances::free_balance(&11), 256000);

		// Set payee information
		assert_ok!(Staking::set_payee(Origin::signed(10), RewardDestination::Stash));

		// Check storage items that should be cleaned up
		assert!(<Ledger<Test>>::exists(&10));
		assert!(<Bonded<Test>>::exists(&11));
		assert!(<Nominators<Test>>::exists(&11));
		assert!(<Payee<Test>>::exists(&11));

		// Reduce free_balance of controller to 0
		let _ = Balances::slash(&10, u64::max_value());
		// Check total balance of account 10
		assert_eq!(Balances::total_balance(&10), 0);

		// Check the balance of the stash account has not been touched
		assert_eq!(Balances::free_balance(&11), 256000);
		// Check these two accounts are still bonded
		assert_eq!(Staking::bonded(&11), Some(10));

		// Check storage items have not changed
		assert!(<Ledger<Test>>::exists(&10));
		assert!(<Bonded<Test>>::exists(&11));
		assert!(<Nominators<Test>>::exists(&11));
		assert!(<Payee<Test>>::exists(&11));

		// Reduce free_balance of stash to 0
		let _ = Balances::slash(&11, u64::max_value());
		// Check total balance of stash
		assert_eq!(Balances::total_balance(&11), 0);

		// Check storage items do not exist
		assert!(!<Ledger<Test>>::exists(&10));
		assert!(!<Bonded<Test>>::exists(&11));
		assert!(!<Validators<Test>>::exists(&11));
		assert!(!<Nominators<Test>>::exists(&11));
		assert!(!<Payee<Test>>::exists(&11));
	});
}


#[test]
fn switching_roles() {
	// Test that it should be possible to switch between roles (nominator, validator, idle) with minimal overhead.
	ExtBuilder::default().nominate(false).build().execute_with(|| {
		Timestamp::set_timestamp(1); // Initialize time.

		// Reset reward destination
		for i in &[10, 20] { assert_ok!(Staking::set_payee(Origin::signed(*i), RewardDestination::Controller)); }

		assert_eq_uvec!(validator_controllers(), vec![20, 10]);

		// put some money in account that we'll use.
		for i in 1..7 { let _ = Balances::deposit_creating(&i, 5000); }

		// add 2 nominators
		assert_ok!(Staking::bond(Origin::signed(1), 2, 2000, RewardDestination::Controller));
		assert_ok!(Staking::nominate(Origin::signed(2), vec![11, 5]));

		assert_ok!(Staking::bond(Origin::signed(3), 4, 500, RewardDestination::Controller));
		assert_ok!(Staking::nominate(Origin::signed(4), vec![21, 1]));

		// add a new validator candidate
		assert_ok!(Staking::bond(Origin::signed(5), 6, 1000, RewardDestination::Controller));
		assert_ok!(Staking::validate(Origin::signed(6), ValidatorPrefs::default()));

		// new block
		start_session(1);

		// no change
		assert_eq_uvec!(validator_controllers(), vec![20, 10]);

		// new block
		start_session(2);

		// no change
		assert_eq_uvec!(validator_controllers(), vec![20, 10]);

		// new block --> ne era --> new validators
		start_session(3);

		// with current nominators 10 and 5 have the most stake
		assert_eq_uvec!(validator_controllers(), vec![6, 10]);

		// 2 decides to be a validator. Consequences:
		assert_ok!(Staking::validate(Origin::signed(2), ValidatorPrefs::default()));
		// new stakes:
		// 10: 1000 self vote
		// 20: 1000 self vote + 250 vote
		// 6 : 1000 self vote
		// 2 : 2000 self vote + 250 vote.
		// Winners: 20 and 2

		start_session(4);
		assert_eq_uvec!(validator_controllers(), vec![6, 10]);

		start_session(5);
		assert_eq_uvec!(validator_controllers(), vec![6, 10]);

		// ne era
		start_session(6);
		assert_eq_uvec!(validator_controllers(), vec![2, 20]);

		check_exposure_all();
		check_nominator_all();
	});
}

#[test]
fn wrong_vote_is_null() {
	ExtBuilder::default().nominate(false).validator_pool(true).build().execute_with(|| {
		assert_eq_uvec!(validator_controllers(), vec![40, 30]);

		// put some money in account that we'll use.
		for i in 1..3 { let _ = Balances::deposit_creating(&i, 5000); }

		// add 1 nominators
		assert_ok!(Staking::bond(Origin::signed(1), 2, 2000, RewardDestination::default()));
		assert_ok!(Staking::nominate(Origin::signed(2), vec![
			11, 21, 			// good votes
			1, 2, 15, 1000, 25  // crap votes. No effect.
		]));

		// new block
		start_era(1);

		assert_eq_uvec!(validator_controllers(), vec![20, 10]);
	});
}

#[test]
fn bond_with_no_staked_value() {
	// Behavior when someone bonds with no staked value.
	// Particularly when she votes and the candidate is elected.
	ExtBuilder::default()
		.validator_count(3)
		.existential_deposit(5)
		.nominate(false)
		.minimum_validator_count(1)
		.build()
		.execute_with(|| {
			// Can't bond with 1
			assert_noop!(
				Staking::bond(Origin::signed(1), 2, 1, RewardDestination::Controller),
				Error::<Test>::InsufficientValue,
			);
			// bonded with absolute minimum value possible.
			assert_ok!(Staking::bond(Origin::signed(1), 2, 5, RewardDestination::Controller));
			assert_eq!(Balances::locks(&1)[0].amount, 5);

			// unbonding even 1 will cause all to be unbonded.
			assert_ok!(Staking::unbond(Origin::signed(2), 1));
			assert_eq!(
				Staking::ledger(2),
				Some(StakingLedger {
					stash: 1,
					active: 0,
					total: 5,
					unlocking: vec![UnlockChunk {value: 5, era: 3}]
				})
			);

			start_era(1);
			start_era(2);

			// not yet removed.
			assert_ok!(Staking::withdraw_unbonded(Origin::signed(2)));
			assert!(Staking::ledger(2).is_some());
			assert_eq!(Balances::locks(&1)[0].amount, 5);

			start_era(3);

			// poof. Account 1 is removed from the staking system.
			assert_ok!(Staking::withdraw_unbonded(Origin::signed(2)));
			assert!(Staking::ledger(2).is_none());
			assert_eq!(Balances::locks(&1).len(), 0);
		});
}

#[test]
fn bond_with_little_staked_value_bounded_by_slot_stake() {
	// Behavior when someone bonds with little staked value.
	// Particularly when she votes and the candidate is elected.
	ExtBuilder::default()
		.validator_count(3)
		.nominate(false)
		.minimum_validator_count(1)
		.build()
		.execute_with(|| {
			// setup
			assert_ok!(Staking::chill(Origin::signed(30)));
			assert_ok!(Staking::set_payee(Origin::signed(10), RewardDestination::Controller));
			let init_balance_2 = Balances::free_balance(&2);
			let init_balance_10 = Balances::free_balance(&10);

			// Stingy validator.
			assert_ok!(Staking::bond(Origin::signed(1), 2, 1, RewardDestination::Controller));
			assert_ok!(Staking::validate(Origin::signed(2), ValidatorPrefs::default()));

			let total_payout_0 = current_total_payout_for_duration(3000);
			assert!(total_payout_0 > 100); // Test is meaningfull if reward something
			reward_all_elected();
			start_era(1);

			// 2 is elected.
			// and fucks up the slot stake.
			assert_eq_uvec!(validator_controllers(), vec![20, 10, 2]);
			assert_eq!(Staking::slot_stake(), 1);

			// Old ones are rewarded.
			assert_eq!(Balances::free_balance(&10), init_balance_10 + total_payout_0 / 3);
			// no rewards paid to 2. This was initial election.
			assert_eq!(Balances::free_balance(&2), init_balance_2);

			let total_payout_1 = current_total_payout_for_duration(3000);
			assert!(total_payout_1 > 100); // Test is meaningfull if reward something
			reward_all_elected();
			start_era(2);

			assert_eq_uvec!(validator_controllers(), vec![20, 10, 2]);
			assert_eq!(Staking::slot_stake(), 1);

			assert_eq!(Balances::free_balance(&2), init_balance_2 + total_payout_1 / 3);
			assert_eq!(
				Balances::free_balance(&10),
				init_balance_10 + total_payout_0 / 3 + total_payout_1 / 3,
			);
			check_exposure_all();
			check_nominator_all();
		});
}

#[cfg(feature = "equalize")]
#[test]
fn phragmen_linear_worse_case_equalize() {
	ExtBuilder::default()
		.nominate(false)
		.validator_pool(true)
		.fair(true)
		.build()
		.execute_with(|| {
			bond_validator(50, 1000);
			bond_validator(60, 1000);
			bond_validator(70, 1000);

			bond_nominator(2, 2000, vec![11]);
			bond_nominator(4, 1000, vec![11, 21]);
			bond_nominator(6, 1000, vec![21, 31]);
			bond_nominator(8, 1000, vec![31, 41]);
			bond_nominator(110, 1000, vec![41, 51]);
			bond_nominator(120, 1000, vec![51, 61]);
			bond_nominator(130, 1000, vec![61, 71]);

			for i in &[10, 20, 30, 40, 50, 60, 70] {
				assert_ok!(Staking::set_payee(Origin::signed(*i), RewardDestination::Controller));
			}

			assert_eq_uvec!(validator_controllers(), vec![40, 30]);
			assert_ok!(Staking::set_validator_count(Origin::ROOT, 7));

			start_era(1);

			assert_eq_uvec!(validator_controllers(), vec![10, 60, 40, 20, 50, 30, 70]);

			assert_eq_error_rate!(Staking::stakers(11).total, 3000, 2);
			assert_eq_error_rate!(Staking::stakers(21).total, 2255, 2);
			assert_eq_error_rate!(Staking::stakers(31).total, 2255, 2);
			assert_eq_error_rate!(Staking::stakers(41).total, 1925, 2);
			assert_eq_error_rate!(Staking::stakers(51).total, 1870, 2);
			assert_eq_error_rate!(Staking::stakers(61).total, 1890, 2);
			assert_eq_error_rate!(Staking::stakers(71).total, 1800, 2);

			check_exposure_all();
			check_nominator_all();
		})
}

#[test]
fn new_era_elects_correct_number_of_validators() {
	ExtBuilder::default()
		.nominate(true)
		.validator_pool(true)
		.fair(true)
		.validator_count(1)
		.build()
		.execute_with(|| {
			assert_eq!(Staking::validator_count(), 1);
			assert_eq!(validator_controllers().len(), 1);

			System::set_block_number(1);
			Session::on_initialize(System::block_number());

			assert_eq!(validator_controllers().len(), 1);
			check_exposure_all();
			check_nominator_all();
		})
}

#[test]
fn phragmen_should_not_overflow_validators() {
	ExtBuilder::default().nominate(false).build().execute_with(|| {
		let _ = Staking::chill(Origin::signed(10));
		let _ = Staking::chill(Origin::signed(20));

		bond_validator(2, u64::max_value());
		bond_validator(4, u64::max_value());

		bond_nominator(6, u64::max_value() / 2, vec![3, 5]);
		bond_nominator(8, u64::max_value() / 2, vec![3, 5]);

		start_era(1);

		assert_eq_uvec!(validator_controllers(), vec![4, 2]);

		// This test will fail this. Will saturate.
		// check_exposure_all();
		assert_eq!(Staking::stakers(3).total, u64::max_value());
		assert_eq!(Staking::stakers(5).total, u64::max_value());
	})
}

#[test]
fn phragmen_should_not_overflow_nominators() {
	ExtBuilder::default().nominate(false).build().execute_with(|| {
		let _ = Staking::chill(Origin::signed(10));
		let _ = Staking::chill(Origin::signed(20));

		bond_validator(2, u64::max_value() / 2);
		bond_validator(4, u64::max_value() / 2);

		bond_nominator(6, u64::max_value(), vec![3, 5]);
		bond_nominator(8, u64::max_value(), vec![3, 5]);

		start_era(1);

		assert_eq_uvec!(validator_controllers(), vec![4, 2]);

		// Saturate.
		assert_eq!(Staking::stakers(3).total, u64::max_value());
		assert_eq!(Staking::stakers(5).total, u64::max_value());
	})
}

#[test]
fn phragmen_should_not_overflow_ultimate() {
	ExtBuilder::default().nominate(false).build().execute_with(|| {
		bond_validator(2, u64::max_value());
		bond_validator(4, u64::max_value());

		bond_nominator(6, u64::max_value(), vec![3, 5]);
		bond_nominator(8, u64::max_value(), vec![3, 5]);

		start_era(1);

		assert_eq_uvec!(validator_controllers(), vec![4, 2]);

		// Saturate.
		assert_eq!(Staking::stakers(3).total, u64::max_value());
		assert_eq!(Staking::stakers(5).total, u64::max_value());
	})
}

#[test]
fn reward_validator_slashing_validator_doesnt_overflow() {
	ExtBuilder::default().build().execute_with(|| {
		let stake = u32::max_value() as u64 * 2;
		let reward_slash = u32::max_value() as u64 * 2;

		// Assert multiplication overflows in balance arithmetic.
		assert!(stake.checked_mul(reward_slash).is_none());

		// Set staker
		let _ = Balances::make_free_balance_be(&11, stake);
		<Stakers<Test>>::insert(&11, Exposure { total: stake, own: stake, others: vec![] });

		// Check reward
		let _ = Staking::reward_validator(&11, reward_slash);
		assert_eq!(Balances::total_balance(&11), stake * 2);

		// Set staker
		let _ = Balances::make_free_balance_be(&11, stake);
		let _ = Balances::make_free_balance_be(&2, stake);

		// only slashes out of bonded stake are applied. without this line,
		// it is 0.
		Staking::bond(Origin::signed(2), 20000, stake - 1, RewardDestination::default()).unwrap();
		<Stakers<Test>>::insert(&11, Exposure { total: stake, own: 1, others: vec![
			IndividualExposure { who: 2, value: stake - 1 }
		]});


		// Check slashing
		on_offence_now(
			&[
				OffenceDetails {
					offender: (11, Staking::stakers(&11)),
					reporters: vec![],
				},
			],
			&[Perbill::from_percent(100)],
		);

		assert_eq!(Balances::total_balance(&11), stake - 1);
		assert_eq!(Balances::total_balance(&2), 1);
	})
}

#[test]
fn reward_from_authorship_event_handler_works() {
	ExtBuilder::default().build().execute_with(|| {
		use pallet_authorship::EventHandler;

		assert_eq!(<pallet_authorship::Module<Test>>::author(), 11);

		<Module<Test>>::note_author(11);
		<Module<Test>>::note_uncle(21, 1);
		// An uncle author that is not currently elected doesn't get rewards,
		// but the block producer does get reward for referencing it.
		<Module<Test>>::note_uncle(31, 1);
		// Rewarding the same two times works.
		<Module<Test>>::note_uncle(11, 1);

		// Not mandatory but must be coherent with rewards
		assert_eq!(<CurrentElected<Test>>::get(), vec![21, 11]);

		// 21 is rewarded as an uncle producer
		// 11 is rewarded as a block producer and uncle referencer and uncle producer
		assert_eq!(CurrentEraPointsEarned::get().individual, vec![1, 20 + 2 * 3 + 1]);
		assert_eq!(CurrentEraPointsEarned::get().total, 28);
	})
}

#[test]
fn add_reward_points_fns_works() {
	ExtBuilder::default().build().execute_with(|| {
		let validators = <Module<Test>>::current_elected();
		// Not mandatory but must be coherent with rewards
		assert_eq!(validators, vec![21, 11]);

		<Module<Test>>::reward_by_indices(vec![
			(0, 1),
			(1, 1),
			(2, 1),
			(1, 1),
		]);

		<Module<Test>>::reward_by_ids(vec![
			(21, 1),
			(11, 1),
			(31, 1),
			(11, 1),
		]);

		assert_eq!(CurrentEraPointsEarned::get().individual, vec![2, 4]);
		assert_eq!(CurrentEraPointsEarned::get().total, 6);
	})
}

#[test]
fn unbonded_balance_is_not_slashable() {
	ExtBuilder::default().build().execute_with(|| {
		// total amount staked is slashable.
		assert_eq!(Staking::slashable_balance_of(&11), 1000);

		assert_ok!(Staking::unbond(Origin::signed(10),  800));

		// only the active portion.
		assert_eq!(Staking::slashable_balance_of(&11), 200);
	})
}

#[test]
fn era_is_always_same_length() {
	// This ensures that the sessions is always of the same length if there is no forcing no
	// session changes.
	ExtBuilder::default().build().execute_with(|| {
		start_era(1);
		assert_eq!(Staking::current_era_start_session_index(), SessionsPerEra::get());

		start_era(2);
		assert_eq!(Staking::current_era_start_session_index(), SessionsPerEra::get() * 2);

		let session = Session::current_index();
		ForceEra::put(Forcing::ForceNew);
		advance_session();
		assert_eq!(Staking::current_era(), 3);
		assert_eq!(Staking::current_era_start_session_index(), session + 1);

		start_era(4);
		assert_eq!(Staking::current_era_start_session_index(), session + SessionsPerEra::get() + 1);
	});
}

#[test]
fn offence_forces_new_era() {
	ExtBuilder::default().build().execute_with(|| {
		on_offence_now(
			&[OffenceDetails {
				offender: (
					11,
					Staking::stakers(&11),
				),
				reporters: vec![],
			}],
			&[Perbill::from_percent(5)],
		);

		assert_eq!(Staking::force_era(), Forcing::ForceNew);
	});
}

#[test]
fn offence_ensures_new_era_without_clobbering() {
	ExtBuilder::default().build().execute_with(|| {
		assert_ok!(Staking::force_new_era_always(Origin::ROOT));

		on_offence_now(
			&[OffenceDetails {
				offender: (
					11,
					Staking::stakers(&11),
				),
				reporters: vec![],
			}],
			&[Perbill::from_percent(5)],
		);

		assert_eq!(Staking::force_era(), Forcing::ForceAlways);
	});
}

#[test]
fn offence_deselects_validator_when_slash_is_zero() {
	ExtBuilder::default().build().execute_with(|| {
		assert!(<Validators<Test>>::exists(11));
		on_offence_now(
			&[OffenceDetails {
				offender: (
					11,
					Staking::stakers(&11),
				),
				reporters: vec![],
			}],
			&[Perbill::from_percent(0)],
		);
		assert_eq!(Staking::force_era(), Forcing::ForceNew);
		assert!(!<Validators<Test>>::exists(11));
	});
}